Design flaws in compact plants for wastewater treatment in food industry enterprises

Abstract

The results of adjustment work, carried out at the local sewage treatment plants of food industry enterprise are presented in this paper. The enterprise has two sites, designed for the treatment of high and medium concentration effluents with a low pH value (3.5-5.5). Concentrated effluents are treated under anaerobic conditions in a compact installation consisting of a waste receiver, an anaerobic bioreactor, centrifuge thickener, centrifuge, flocculant preparation units and reagents. Wastes of medium concentration after neutralization are treated under aerobic conditions. The structure of this compact unit includes first-stage flotators, aerotanks operating for incomplete biological treatment, and second-stage flotators. Foam of the first stage and excess activated sludge of flotation devices of the second stage are dewatered on filter presses without treatment. The essence of the commissioning work consists in a detailed analysis of design solutions for both sites, study of the wastewater composition of high and medium concentration, systematization of operational data, which will allow operation to select the optimal operating mode of the main structures (anaerobic bioreactor and aeration tank). On the basis of the performed work, the optimal technological scheme of the unit for anaerobic digestion of high-concentration effluents has been developed and proposed. It is recommended to abandon the use of reagents, introduced before the flotation devices of the first and the second stages, due to an increase in the working pressure in the saturator for a compact installation designed for the treatment wastewater of medium concentration.